A conventional cooling fan module for a radiator of a motor vehicle disclosed by EP1050682A2 includes a fixed support structure, a DC electric motor, particularly a brushless motor, and an impeller. The support structure includes an outer frame, an annular inner seat, and a plurality of spokes connecting the annular inner seat to the outer frame. The electric motor includes a stator fixed to the annular inner seat of the support structure, a rotor mounted to the stator, and a circuit means, the components of which are in thermal contact with an essentially plate-like heat sink which extends transversely with respect to the axis of the motor at a first end of the stator. The impeller is fixed to the rotor of the motor at a second end of the stator and having a hollow hub from which a plurality of outer blades extends. The hub has an annular front wall intended to the struck by the air flow caused by the fan and a side wall extending from a circumferential edge of the front wall. The side wall surrounds the motor defining an annular space with respect thereto. The hub is further provided with a plurality of inner ventilation vanes which extend from the inner surface thereof and are adapted to generate in operation, within the annular space, a flow of cooling air which contacts the motor and the heat sink.
In this conventional fan module, a flow of air is drawn in by the rotating hub and arrives at the rear end of the motor where the heat sink locates. This flow then passes through the electric motor, in the direction from its rear end towards its front or anterior end, thereby cooling the heat sink associated with the internal electronic control circuits, as well as the motor itself. At the front end of the motor, this air flow is diverted radially outwards, and enters the annular space formed between the side wall of the fan hub and the motor. In this space, the air flow is propagated from the front end of the motor towards the rear end thereof, and is discharged outwards at the outlet end of the impeller hub.
One object of the present invention is to provide a fan module which is appropriately improved, particularly in order to provide more effective cooling of the heat sink mounted at the rear end of the fan motor.